There are several techniques for identifying the distance, location or speed of moving and fixed objects. One such technique is radar, which uses radio waves provided by a transmitter, and detects reflected waves to determine the location or speed of an object located some distance from the transmitter.
Laser-based techniques can also be used to provide such information. For example, LADAR (Laser Detection and Ranging) and LIDAR (Light Detection and Ranging) direct electromagnetic waves toward an object from a source (e.g., a light source or laser). The object reflects a portion of the waves, and the reflected waves are detected by one or more sensors, such as photodetectors.
Such techniques can be used to determine the distance between the source and the object based on the round-trip travel time from the source to the object and back to the sensors. The velocity of moving objects can also be estimated using such systems based on, e.g., the rate of change of the phase differences between the transmitted waves and the reflected waves.
The imaging of distant objects and scenes can also be performed using such techniques. However, such systems generally use an array of detectors, and the resolution is often limited by the size of the array, e.g., the number of detectors or pixels in the sensor array.
Accordingly, there is a demand for imaging methods and systems which can provide imaging of objects and scenes using a small number of detectors or transmitters, for which the achievable spatial resolution is not limited by the number of detectors or bandwidth of the system.